You might have to think a little more about the problem statement. Cade's class diagram indicates how a class diagram submitted for the exam should appear like.So, dont be surprised if it appears similar but i believe
you should fully explore your problem statement, the business domain,etc.
Obviously, i cant speak much because of oracle's exam policy but your intent should be to ensure that you have all the angles to your problem statement covered.If you have, and it's still looking like what cade has shown, so be it.
If you can think aloud toall the problems that can appear in such a system and then cross examine yourself to indicate how your solution addresses it.You should be fine.
OCMJEA/SCEA, SCDJWS, SCBCD 1.3, SCJP 1.4
My SCEA experience:http://javalogue.blogspot.com/