she was - at least part of the time - painted white-buff (with most important Brazilian ships built in Britain, it's probably not too wild a guess that they bought their paint there as well, so RN colours seem likely); later she sports standard grey.
I seem to recall an old Morskaya Kollektsiya issue that had an image of Barroso with white hull, now that you mention that... I'll see if I can find it.