Which proposition should I use

I graduated with a higher diploma in Mathematics.

I graduated from the University of Hong Kong.

You should use "in".

I will rewrite it as following

I finished the higer diploma course in XXXX at School name or University name.

We say we graduated from a school or university or Iwe finished the higher diploma course in xXXXX

因該是 from. 不過不是太確定。錯了真是對不起。還是再看看其他人的回答吧。