AUGUSTA — The city Planning Board approved a granite-and-flint-colored facade for a proposed new state office building, a color scheme that board members said fits in better with the nearby State House complex than the previous proposal. The project developer that will put two new office buildings at the former site of the state Department of Transportation maintenance facility had originally proposed white cement wall panels. Board members clearly favored the granite-and-flint option, which member Alison Nichols said is a better match for the stone state buildings, including the granite State House itself, which are nearby.