Per Paul's paint scheme tables the TO-20 painted the starter and genny grey like the castings. He lists the TO-30 having flat black painted starter and genny.
He also included this note: Promotional literature, manuals, and other visual media sometimes showed these items as painted black and sometimes painted the colors of the castings. Often these were photos from pre-production prototypes. The color schemes shown here lean toward those used on production-line units. However, it is not unreasonable to assume that assembly sequences may have changed in mid-production for any particular model. Use of paint schemes shown in promotional literature and manuals is perfectly acceptable, depending upon the preferences of the restorer.
BTW, Learn to spell color correctly Sam. :)