My coworkers went all out for me for my work shower. Seven of them went in together and hosted lunch and cupcakes for my department (and anyone else in the company I wanted to invite). They decorated the lunchroom in my nursery theme and we even did cake tastings to find the right cupcakes to get. And the gifts from all the attendees were phenomenal!!!
During the shower, I hosted the "shower game", meaning that I thought up and put together the game myself (at my own cost). I also had a diaper raffle, for which I bought the raffle prize.
As a thank you to the ones who planned it, I gave them each a little gift. Travel coffee mugs, candles, etc. I went more personal for the few who I knew even better. One mentioned that she liked my (designer) nail polish, so I bought her a bottle of it as my thank you to her. In addition, I gave all the gift givers each a thank you card.
These were my coworkers, not my family. They had no obligation to do anything for me, and I was so touched! So I probably spent a lot of my own money on the shower myself, but it was the least I could do for their thoughtfulness.
If they give you one big group gift, then at a minimum, I think a thank you card to each person would be in order. After all, they put in the money as individuals, so you should individually acknowledge their contribution. If you want to host a game during the shower, I can help you with a fun group game that male/female coworkers can play! (And not be grossed out.) Have fun!