Painting it darker will help, but it will work a lot better with an air gap
and glazing and airflow through the house during the day. You might paint
the aluminum siding darker and a) build a deep picture frame on the wall
with 2x6s on edge and polycarbonate over that, or b) make a sunspace that's
4' or 8' deep with a dark mesh curtain (eg 80% greenhouse shadecloth) 1'
behind the glazing, which adds useful floorspace to a house.