how do i found out What color my paint is its a 1991 grey gun metal color its a 940 turbo if vial matters

 

also What color would look good with the gray color blue red sliver for brake caliber

 

Maybe in the door pillar but most Volvo's in the '90's have a plate in the engine compartment that has the color code on it.

I would think RED, BLACK or SILVER.

 

paint color codes are found in several places. There's an adhesive tag under the trunk lid, A riveted plate on the passenger side B pillar or edge of the door, a plate on the edge of the driver door, two potential plates located in the engine bay. One might be on the metal by the hood latch another might be located on or near the strut tower. All kind of depends on where your 940 was put together.

You said yours was a gray gun metal color? Probably the dark gray metallic: paint code #214

red is cliche, silver is boring...Black wouldn't be bad. IMHO, the only way to really pull off painting your calipers to stand out is if they're upgraded after market. Otherwise it's just a poser look.