One can use a vivid palette for this coloring page. For a cheerful sky, one can use a bright blue color with some white clouds. For the sailboat, one can choose a light blue and white color combination to create the illusion of movement. The sky's reflection can be portrayed in shades of white, gray and blue. The people on the boat can be colored with vibrant hues of yellow, green and red, while the sea can be filled with different shades of blue. Furthermore, the sun can be added with a bright yellow and orange combination to give a vivid and energetic feeling to the illustration. This coloring page can also be enhanced with some small details like stars in the night sky, seagulls or tiny boats in the distance.