The color is the giveaway. Males are the only ones that have that red leakage on the wing/shoulder area. Females don't have that coloring.
With that coloring, we didn't need to ask about the age of the bird. If it were a solid color, I would have asked about age. The size and redness of the comb would then be the key. Plus, this is a pea combed bird. Pea combed females have smaller combs with usually one row down the middle. Male pea combed birds have the three rows, and it's larger and plumper. Pea combed birds have small wattles, so that can throw folks off sometimes.