In this coloring page, you can see two men. The figure on the ladder is wearing a dark colored shirt, and light colored pants, and is holding a long brush in his hand. The figure on the ground is wearing a light colored shirt and dark colored pants. The man on the ladder appears to be painting or fixing something, while the man below looks as if he is providing guidance or offering advice.
I would suggest to use bright colors for the clothes of both figures. A contrast between the two could look great, for example an orange shirt for the man on the ladder, and a light green for the man below. The walls and windows around them could be colored in a subtle off-white, and the ladder in beige. The brush and the tools on the ground could be in vibrant colors like yellow, orange or blue. Doing this would act as an accent in the overall coloring of the page.