Easiest way to get from Cinque Terre to Venice

Molly, My what method of transport? Train, bus or car?

If you want to go by train, the Trenitalia (Italian Railways) site will give you the answer: https://www.trenitalia.com/en.html
Enter From: whichever of the 5 towns you are starting from (Monterosso, Vernazza, Corniglia, Manarola, or Riomaggiore)
To: Venezia S. Lucia and desired date and time, then click on [Search]

This will always find the quickest route. This will take about 5-6 hours.
You can't do much about the number of changes of train (transfers) required. The train routes are fixed, unless you want to charter a whole train to go direct from your starting place to Venice☺!

Molly, your problem here is that choosing an option with the least amount of changes may significantly increase the amount of time it'll take you to get there or have you departing much later in the day than you might prefer. Also, the Cinque Terre isn't just a single place: it's 5 separate villages (Monterosso, Vernazza, Corniglia, Manarola and Riomaggiore) with their own train stations.

So, where will you be staying in the CT and what time of day do you want to arrive in Venice (earlier in the afternoon, later in the afternoon, or evening?)

Thank you both for the reply. I've now made my arrangements with only one transfer. I appreciate your replies.

Just curious: what option did you choose? I think the only choices with a single change (all at Milano Centrale) are:
6:54>14:40 from Monterosso (7 hr; 46 min.)
12:55>18:40 from Monterosso (5 hr; 45 min.)
14:55>20:40 from Monterosso (5 hr; 45 min.)
16:55>22:40 from Monterosso (5 hr; 45 min.)

So, I'm guessing you're staying in Monterosso?