Is your degree in an exercise science/ex phys degree? I took the CPT exam and wished I just took the CSCS. Your are going to have to get a basic understanding of ex phy, anatomy, kinesiology, and of course matters of weight training.
The NSCA offers test prep materials. They are kinda pricey, but if you are lucky you can find them on ebay. A good start is to pick up the "Essentials of Strength Training and Conditioning" published by the NSCA.