<human>: I [21F] am graduating college in December and would like to ask out a [27M] professor after I graduate.

This is his first semester teaching and he is a professor in the department that I am getting my degree in but I've never had him for class nor am I going onto a career in the field and this is my last semester.

I started talking to him at a department event at the beginning of the semester and we had a really good talk and now I hang out with him  sometimes when he doesn't have anyone coming to his office hours and we always have a good time laughing and joking.

I want to ask him out for coffee after I graduate in December. Is this okay to do? and If so, how do I ask him to make it the most okay? I was going to give a card to some of the professors that I did have in the department thanking them for teaching me and I was thinking about giving him one too and saying how it was nice to meet him and tell him I'd like to get coffee with him sometime and write my cell phone number and tell him to tell me if he is interested.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: I [21F]want to ask a [27M] professor at my school (who never taught me) out after I graduate this December. Is this okay? and if so, how do I do it?