I would bring a card either way and maybe a bottle of wine, dessert or some type of food item that could be served that day or saved for later.
As for a gift, if it were someone close enough that I would give a graduation present even if there wasn't a party I would still do so but not at the party if asked not to. I would have it sent or bring it another time.
Another alterntive, something we often do is to make a donation in the persons name to a cause or charity that we know they are concernd about.
TJ