L.H.
How about stations with games. You could have separate tables with card games/dominoes/dice games, etc. If you wanted to do a big group thing, charades maybe or pictionary? You could even divide into teams and do it like a tournament, having prizes for the winning team (wouldn't have to be expensive, just some little something). I think most people enjoy playing games and if you use traditional ones, everyone will already know how to play.
Congratulations on your graduation and God bless you as you start this next chapter in your life!
L.