You could go with a smashing pair of heels, like these ones from Dior. But if your school is anything like mine, then you're going to be walking on grass. I haven't personally tried it, but heels sinking into the mud and getting dirty does not sound enticing. So you can either brave this or. .
. . you could try flats. Something pretty like these ones from Marc by Marc Jacobs and Miu Miu wouldn't be too bad. Makes it more casual. But this IS graduation and you don't really want to be that casual. Plus, some height would be nice.
Luckily for us, wedges are super trendy this season and they are everywhere, because they are PERFECT for graduation. They look as smashingly fabulous as heels AND it won't sink into the grass!!! I especially LOVE these two from Miu Miu and Christian Louboutin. They're both made of patent leather (so won't get dirty so easily) and the styles are both very classic and elegant. Perfect for both formal or casual occasions. Plus they are the just the right height. Just tall enough to give height but not so tall that it'll be the devil to walk in.
Or if you can take it, there are these two higher more strappy wedges from Kate Spade and Miu Miu. I don't reckon the thin straps would be too comfortable, but your feet will look GORGEOUS!
Darn, I wish I was graduating too!