Well I think first you need to decide exactly what you'd like to do. And second, see if your current company may have what you're looking for. It is possible that over your first 2 years or so you will get a much better idea of what you'd like to do. From then, you can decide if you'd like to stay with your company, and if there are any opportunities for you there. If not, some programs offer an option for people JUST like you. It's a program where you actually leave your job after the first two years of classes, you take on an internship in your new desired area (just like the full timers will be doing), and then do that last year (6-9 months) full time. Then you either start a full time job with your intership company, or move onto bigger and better things in the area you have now realized you love, and you'll have a great story of how you've come to love the job they're offering. These programs are designed for the people that want to do a full 180 turn. They obviously need that intership experience, but can't get it at their current company. You would be the person only making the 90 degree turn. Plus you'll have 2 more years of work experience compared to someone else your age with an MBA.
I would definitely consult with the career center at your school, and see if they have any ideas for you too. Also, open up a line of communication with your manager towards the end of those first 2 years. You will need to read the employee handbook also, because often times they have rules about switching groups within the company.
Good luck! I think you will quickly have some great ideas of some areas you might see yourself in. And who knows, maybe they'll be with Citi.