Well the number of paint jobs appear to be at least 3 according to the manual. i.e. 1 paint job per Hot Rod mag found.
Added these pics I took from the manual with my smartphone. So far, there appears there is a custom Red (confirmed as I've found this mag), pink? and what appears to be white? paint job from the pic below.
Some PA armor color schemes. Apologies for the poor quality:
http://imgur.com/wovgfRP
Custom Hot Rod Paint scheme (red theme) for the T-60 which boosts the T-60 PA's agility. Need to have found the corresponding Hot Rod mag to unlock this particularly paint job:
http://imgur.com/qKurxEQ
X-01 sunset orange custom job:
http://i.imgur.com/EwIgQNC.jpg
X-01 titanium plating version:
http://imgur.com/xYtolLu
Unfortunately, the manual was incredibly incomplete on what each custom paint job looked like. 
It seems this modder found a way to unlock? and/or add textures for the X-01 and also added 8 extra colors for the T-60. But be aware this texture mod also has a unofficially sanctioned, pre-GECK esp which could potentially create issues in your save game (i.e. if modder used TESVSnip for example to create the esp)
http://www.nexusmods.com/fallout4/mods/2249/?