Cape colors vary for a reason! If you have longer hair, then hair professionals need to be able to see what they are cutting. If you have black hair and a black cape draped around you, then you may not get precision in your haircut! So if you have light colored hair, then the black cape works out great! Black capes are the most common color for capes because they match every salon's decor. However, if you have black/dark hair, ask the stylist for a lighter color cape or a lighter color towel to go on top of the black cape in order for you to see your true hair density.
Pictured is an "over the shoulder" drape by the company "Hair Art" to assist in haircutting at a 180 degree angle. (i.e. straight down) There are actual weights built into the front side to keep the drape from slipping off as you cut. The cutting trend is a straight across cut; so this drape is best used when someone wants a bell shape.