The Princeton Companion to Mathematics [1] is good if you want to gawk at the breadth and depth of the field. For actual education I would just suggest looking at a math department's syllabus, e.g. at http://ocw.mit.edu/. As a CS grad you should start with analysis, as that's probably your most looming dark spot.
My warning as a math student is that a lot of book recommendations are just a tad bit elitist. Don't stick with a single book too long if it isn't cutting it for self-study. Exercises are good.