Good stuff Michael, and there is no doubt that von Werra's aircraft, as with all JG3 aircraft, carried the white bands, rather than yellow.
This was the earlier colour used for rapid I.D. in the air, introduced in mid-August 1940, but fairly soon replaced by yellow, as it was more visible against the bright sky background, and the areas painted in this colour gradually increased during mid to late August, evolving from wing tips and a rudder segment, to eventually, the entire engine cowling and all of the rudder and, in some cases, all of the tail area.
It would seem that some of the Gruppen or Staffeln of the unit were rather slow to change over to yellow, as at least von Werra's aircraft, and that of Heinz Schnabel, among others, still had white markings in early September.
Interestingly, having very recently watched, again, the 1958 movie "The One that Got Away", starring Hardy Kruger as von Werra, it seems that the film's producers and art department got things right, as the very convincing replica of von Werra's aircraft used in the opening scenes appeared with the correct, clean colour scheme - although the film showed the canopy opening the opposite way, presumably due to camera angle considerations, an allowable error in the circumstances !
Even just for background interest, it's worth watching this movie (it can be viewed online, free), as it is a fairly accurate, and very interesting portrayal of his crash-landing, capture, interrogation, escape attempts in England, and eventual successful escape from Canada.