Basically, Liberty Ships were painted in Measure 14, overall 5-O Ocean Gray...in FS #, that equates to 35164.
Some ships under navy control were painted in Ms 21 and 3x camo schemes, but the vast majority, including the O'Brien, were Ms 14. Here's the official instructions:
Vertical Surfaces:
Vertical surfaces from boot-topping to top of superstructure masses, Ocean Gray 5-O.
Pole masts, yards, slender upper works above level of top superstructure masses, Haze Gray, 5-H.
Horizontal Surfaces:
Horizontal surfaces, Deck Blue, 20-B.
Wood Decks.
Wood decks except on submarines and carriers shall be darkened to the color Deck Blue. Deck Blue paint shall be used in lieu of stain for this purpose.
Canvas Covers.
Canvas covers visible from the outside vessel are to be dyed a color corresponding to Deck Blue.
Notes:
The camouflage painting need not be exact or carried into corners. Small gear, wires, rigging, and areas permanently in shadow, as under boats, etc., need not be painted with the camouflage colors. There is no objection to exact or careful painting which may be desired for the sake of good appearance at close range.
All bright or shiny objects, no matter how insignificant, shall be painted, covered, or removed.
Glass windows shall be covered or removed, especially during the day in sunny weather, and at night when anticipating searchlight discovery. Insofar as conditions permit, similar precautions shall be taken on airport lenses.
Hope that helps...
Jeff