A few years ago, when nobody had covers, I discovered
snap-caps and got a bunch.  I'm still using them....

They didn't then have an exact match to Westy gray,
but something close.  I actually got their hinge-caps.
A good thing is that you can use them to cover other
screws, not just the original Westy screws with the
head that grips the Westy cap.

http://www.pro-dec.com/screw-caps-screw-covers/snap-caps

Richard