Overall yellow Fw-190A-6 ???

Pierre Clostermann mentions, in his book "The Great Circus", he saw a
dogfight between a Spitfire of his squadron and an FW 190A-6 piloted
by a certain "Major von Graf", nicknamed "Donald Duck" by the Allies.
The Fw was, according to his book, painted in overall bright yellow
scheme and, curiously enough, I couldn't find any other reference to
that specific aircraft, supposedly from JG.2, neither about this
"Major Von Graf". I guess such an exotic aircraft would be mentioned
at least in one or other book, specially considering it was flown by
the CO of the Jg.2. Does anyone have any reference material, picture
or whatever about this plane?

Tks in advance,

Vicente