More Value?
There are various reasons why a color "might" make a vehicle more valuable. Was it the least color selected, how many where made, was it a one-year color only or was it offered over many years? Did it become available only in limited edition models? Perhaps as anniversary paint schemes i.e. 25th, 30th, 40th or 50 years, or maybe a special edition model i.e. (Indy pace car)
If Violet (blue/purple) SSRs were only made for the first 25 Signature Series and was held to only few limited numbers after that, it just might bring a larger premium!
Ps I agree with carnut, take care of your vehicle and keep a history log of its journey along the way and that should add to it's value/desireablity!