There are several opinions as to what color Crescent originally painted their machinery. Whatever the original color was, machines with their original paint tend to have significantly faded over the years making an exact match nearly impossible.
It is generally agreed that the early machines were painted a flat black (no gloss in the paint at all). I have not heard of anybody that has gone to the trouble to match the paint perfectly but I imagine that some plain old flat black Rustoleum would do the trick.
Some old machines appear to have been painted a very dark smoke gray - with almost a hint of blue. A close match to this color is to take a quart of Rustoleum Flat Black and mix a small 8 oz can of Rustoleum Gloss White.
Later machines were painted a standard Machinery Gray - similar to the old Delta and Rockwell machines.