Traditionally WP springs have been white.

Traditionally WP springs have been white. From their website:

Right from the beginning, the springs that were used on WP shock absorbers were white, which became the typical WP colour. There’s a nice anecdote to the circumstances that led to the "choice" that was made for this colour. In the beginning the springs were coated by a company that produced hospital beds and white was the only possible colour for them (!). Although, nowadays the coating is done by special spring coating companies, the WP shock absorbers can still easily be recognised by the white springs. The white springs also introduced the original brand name of "White Power" which we are not using actively in the market anymore since 1991.

The initials of the founder are also WP (Wim Peters), but that is purely by coincidence.