McCarthy’s entry in the Author Price Guide lists several variations of All The Pretty Horses.
One is bound galleys, in black tape with smoky acetate cover. Apparently, this is the earliest form of the book.
There’s an uncorrected Proof, in mauve wraps, subtitled “A Border Trilogy.” A second and third state of this one exist, as well.
The signed copy you’ve seen appears to have been the last one before publication.
My source for all this is the Author Price Guide from Quill & Brush books at http://www.qbbooks.com. It provides much more detailed information, and it’s a necessity if you’re serious about collecting McCarthy.