Can someone tell me what kind of job a computer graduate does?

Software engineering is programming, plain and simple. It could be application development, database programming, web page design, or anything else that requires programming. You could also specialize in a certain environment, like SAP. It all depends on what you want to do. If you were to minor in business management you could have a strong foundation to become a project manager (PMP). As far as it being draining, it depends. For example you could become a freelance web developer and set your own hours. Or if you happen to enjoy what you're working on it will be less of a chore. It's really subjective, but I hope this sheds a little light on it for you.