The party is a celebration with the Graduate at the centre of the festivities.  That said; there are no rules.  The party could be anything from an intimate gathering of family in your backyard to a ballroom filled with everyone your child knows, even your local bowling alley. 
No matter what you choose, remember it’s not about you, it is the Graduate.  Your child has made a great achievement and through that, the party can take on an element of the Graduate.  Mix in a little bit of their hobbies, their favourite sport or entertainment.