Looks like the College Board sells individual subject guides for $10 -
"The English Composition exam assesses the writing skills required in
most first-year college composition courses writing that explains,
interprets, analyzes, presents, or supports a point of view, as well as
the ability to apply the principles and conventions of standard written
English. Two versions are available: an all multiple-choice version and
a version with an essay. This examination guide contains a complete
exam description, including knowledge and skills required, 50 sample
questions and answers, sample essays, and essay topics. The examination
guide also includes chapters from the CLEP Official Study Guide, 17th
Edition: Preparing to Take CLEP Examinations, Taking the Examinations,
and Interpreting Your Scores."
Check out:
http://store.collegeboard.com/productdetail.do?Itemkey=050061563
Or
"Review for the CLEP General English Composition Examination" and "Cracking the CLEP" seem to be highly rated by Amazon customers ...
Good luck! When are you taking the exam?