Looking on the internet deeply has found these results:

graduated from is the most popular phrase on the web.

graduated at 1125,000 results on the web	graduated from 172,700,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
I graduated on Faculty of Economics. 5. I graduated at the Faculty of Economics .. .or maybe a new example? Thank you very much in advance�... This nigga graduated at the top of our class. I went to Cheesecake, he was a motherfucking waiter there [Hook] [Verse 2] I got a Jones like Norah for your soror ' Farrow attended Bard College at Simon's Rock and graduated at age 15. In 2009 , after deferring admission for several years, he graduated from Yale Law�... May 31, 2011 ... Both phrasings were used in the 19th and 20th centuries, according to the Google Books Corpus, as was "be graduated at." By is the standard�...	It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

graduated at

1125,000 results on the web

graduated from

172,700,000 results on the web

More popular!

I graduated on Faculty of Economics. 5. I graduated at the Faculty of Economics .. .or maybe a new example? Thank you very much in advance�...
This nigga graduated at the top of our class. I went to Cheesecake, he was a motherfucking waiter there [Hook] [Verse 2] I got a Jones like Norah for your soror '
Farrow attended Bard College at Simon's Rock and graduated at age 15. In 2009 , after deferring admission for several years, he graduated from Yale Law�...
May 31, 2011 ... Both phrasings were used in the 19th and 20th centuries, according to the Google Books Corpus, as was "be graduated at." By is the standard�...

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.