How can I get his attention?

Hey he is probably thinking the same as you. He doesn't want to lose contact with you either just he's waiting for the right time to say it. The connection is there. You guys definitely are cool. In your position your a woman. You have it easier than a guy because when a girl wants something she usually gets it her way. It's all a game though that's what it basically is. He is playing the hard to get role on you and it is working actually. He will not say NO. You guys have that chemistry going on so don't worry about getting a NO answer. Just how you are straight up here tell him. "I want to keep in touch with you. How can we contact each other since we won't be in the work environment for a while?" That is asking him indirectly for his number or email or something! You're not asking him for his number like let me get your number. That is a little aggressive. It makes him think too about what you are trying to say so it can mean to him a lot of different things. He could think you just want his number because you're good friends or want his number to date him! The way you put it there is in a way that is less aggressive and smooth. He will get what you're trying to tell him. Girls always have done this way of approach to me. "I love this jacket I wish I had it." They say it so I can get it for them. You feel me?

Ever consider that maybe he's interested in you but is scared to do anything about it because of the fact that you work together and dating a co-worker is always a tricky thing. In any case I think now that school's almost out is the perfect opportunity to date because summer vacation is here and you can go out without worrying about the work-place environment as much.
My best advice is to ask him to get lunch together, say something like "School's almost done for the year, we should celebrate getting through it, how about grabbing some lunch together?" It's a safe, easy, friendly way of showing interest without coming on to strong. Then just go with the flow during lunch, talk and if he's into you he'll ask you for your number. And if not, you could always give it to him anyway when you leave and say something like "This was fun, we should do it again over the summer sometime, here's my number". Hope it all works out.