Either the lights or the clear lens were blue. They were located about half way out along the wing just ahead of the aileron, inboard of the middle aileron hinge. Here is a color picture that isn't very distinct.
Here is a picture of the underside of the wing.
And finally, here's the underside of the wing of a restored Bearcat with what looks like a blue lens exactly where if appears in the wing in the above pictures.
I wrote "some" F8Fs because this is a lower resolution picture of a much higher resolution one taken of an F8F-2 during a Grumman acceptance flight and there is clearly no light installation on the outboard wing panel. Note however that there is a white light on the top of the fuselage just ahead of the dorsal fin.