The ones tearing up and sniffling and trying to grab everyone they know to take as many pictures as possible:

Taurus, Cancer

The ones who got too excited throwing their graduation cap really high and maybe accidentally stabbed someone with it:

Aries, Sagittarius

The ones who are pretty much covered in all kinds of medals and ribbons:

Virgo, Capricorn, Pisces

The ones who are impatient to go home because it's freezing/ unbearably hot outside and they are forced to sit through the whole ceremony:

Libra, Scorpio

The ones who instantly disappeared as soon as the last speech is finished:

Gemini, Leo, Aquarius

The valedictorian:

Capricorn