Paper maps of rail system?

Do you mean paper maps of the public transport system in Amsterdam? Or a map of the rail network of the Netherlands? If it’s the latter I’m not sure how that could be helpful, because it doesn’t include departure times, journey times etc.
The best tool to plan day trips is a travel planner like Google Maps or https://9292.nl/en or the planner of the national railway company https://www.ns.nl/en

short answer - I've never seen one. There is a graphic map on display but not to take at the bigger stations. You can enlarge online ones. There are a lot of stations, to fit it all you will need a big piece of paper, or several.

NS used to have a paper timetable book for the whole country which contained the system map- the Spoorkaart van Nederland.

My copy (the spoorboekje) is just over 800 pages long. It also includes the ferries from Enkhuizen, Breskens and to the five Friesian Islands, plus all international services.

I am looking at my copy now. I haven't seen that book in years but NS still produce the map in PDF form on their website- which you should be able to print (maybe on A3), or just save to your computer and blow it up to larger size there- https://www.ns.nl/binaries/_ht_1676536351229/content/assets/ns-nl/dienstregeling/nieuwe-dienstregeling/ns-spoorkaart.pdf

A quick google shows that the spoorboekje is in fact still produced, but the 2024 edition is currently out of print- https://www.ovshop.nl/shop/spoorboekje-2024

But even if the OP prints out the map of the rail network, how can they use it to plan day trips? The numbers and colors don’t mean anything, unlike in the Paris metro map.
The map doesn’t tell how long it takes to train somewhere, it doesn’t tell when the train leaves and it doesn’t tell from which platform. And most importantly, a map doesn’t provide up to date information about delays, track works, platform changes etc etc. You need to use the journey planner for that kind of information.

I am looking at a map that just shows the stations and the proximity to one another - for example, if we visit Delft, it looks like the Hague and Rotterdam are relatively close by. I don't really need a schedule. I thought if I could pick up a map at the first station we arrive at (Amsterdam) we could study it to decide where we want to go the next three days.

I did try printing one out by it was pretty small! I guess we can make do. It's not a big deal in the grand scheme of things! :) Or we will just use the online maps.

Thank you for your suggestions.

have you thought of looking at a paper map of the Netherlands or perhaps paper maps of one or provinces? They will both have the main train lines on there, and you can pretty much be sure that every significant town and city will have one or more stations.

Once you decide that if you are in Delft and you want to go to Rotterdam you can then look that up.

When you are looking at Rotterdam be aware that what looks like train tracks is often the Rotterdam metro, and in The Hague and Delft they are linked not only by trains (The Hague has two main stations) but by trams.

For a pretty petite country do you really want to be combing through 800 pages? That shows you that there is a lot of public transportation.

If you can’t find a useful railway map you can use a good roadmap too for marking the places of interest and using the above mentioned planning tool of our national carrier NS. Know that the larger places have always railway stations and are well connected with eachother. When in doubt you can use online maps like isn31c suggests or this one: https://spoorkaart.mwnn.nl/

Amsterdam, Leiden, Den Haag / The Hague, Delft, Rotterdam are on the same railway line and to reach without any change. You can even hop on and off as much as you like with a single ticket, but no back tracking and detours allowed and only the day it's issued for. Haarlem and Utrecht however in different directions have a direct connection with Amsterdam too. Likely this will cover the majority of your train travels, so easy to navigate. But for planning and having an overview as you want you can do the above suggested.

A paper map of the rail system will show you that Delft is close to Den Haag, but that is something any map of the Netherlands will do. What that map will not do is tell you that often the easiest way to get from Delft to Den Haag is by tram.
The proper way to go about this is not to worry about what type of vehicle or public transport line will get you somewhere. The public transport system in the Netherlands spans the whole country. Just use the NS app, or the 9292.nl site to just find the best routing.