Liberty ships

Since she was an SS and not a USS it's very likely she wasn't painted in official Navy colors. The Navy essentially told Maritime commission ship builders who asked for Navy paints or paint chips to go pound sand at least until 1943, and then after that only released the specifications and would not supply paint.

You could try contacting them and  asking what they're doing on her now...

They were some kind of gray, but after a few days of dirt, soot and rust, it doesn't matter what kind of gray.  I wouldn't obsess over it.  In most cases the whole ship was painted with the same color.

Fred

Also the O'Brien gets repainted courtesy of the USN these days, whatever colors they happen to be using.