Do you need a book to teach yourself the subject matter? Or are you looking for a test-prep book?
If you need a refresher on college algebra, I'd suggest
Khan Academy or
Virtual Math Lab - College Algebra.
To prepare for the test, I'd recommend taking practice tests. Sources for practice tests are here:
Degree Planners - Sample Questions and Practice Tests
The College Algebra CLEP has 60 multiple choice questions, and it's scored on a scale of 20 to 80. Colleges set their own requirements for passing, but the American Council on Education recommends 50 as passing at a C and 63 as passing at a B. So if your college accepts this CLEP, chances are the score they require is between 50 and 63. (In my experience, 50 is the most common passing score.)
For information about the scope of the is test:
CLEP: College Algebra 
