The colour of your wing can make a difference in terms of visibility. Brighter coloured wings are generally more visible than darker ones. In the case of an accident in a remote place, a brighter-coloured wing could increase the chances of being spotted by the emergency services.
The most important factor in avoiding a midair collision in crowded skies is good airmanship by avoiding situations where midairs are possible and always being highly vigilant. However, there is a chance that the colour of the wing could make a difference in terms of a potential midair when in crowded skies.