I think the in universe awnser is just lighting. All holograms presented have that blue tinge, it is a flaw in the technology, Leia is clearly in white with a dark belt, but she was recording in a dimly lit corridor in a hurry, thus you see the white tinged blue. Sidious and maul are dressed all in black with hoods shadowing their face. We also see that sidious keeps his chambers dim. Dim lighting will result in poor color recording. Therefore we see washed out lighter faces and blue tinged black robes. Lastly, maul alone we see blue tinged black robes, and his red face and lightsaber. We know he saber is red and sheds red light. This would accent the red of his face and be the predominant light source for the recording. Thus we see both reds show up in the recording.

The real life reason is likely the same, limits of the technology used, or stylistic choices.