@Fat_imyy both are good, depends on how fancy her wedding is, and where its being held, dont want to out dress the bride. #2 is more formal, both are nice
@MrPitbull07 you said it was a group of people, so that was why the big amount, people can only tip what they can afford. And how long did she spend serving? 40 might have been a bit skinny, then again its a tip not a bill.