There is one book called "Elvis Fashion" that has a couple of chapters about the jumpsuits but it is scratching at the surface. Another which has a tourlist with jumpsuits is "Elvis-The Concert Years, 1969-1977" from author Stein Eric Scar but that one contains a lot of mistakes.
If you like I can provide you with an up to date tourlist with not only the jumpsuit he wore but also the belt, cape and guitar. It's only a tour list which means it contains no information about the Las Vegas seasons. That's an airea that still needs exploring.