This vibrant coloring page depicts a brave princess, facing off against a huge green dragon in the foreground. In her tiny hands, she wields a crude weapon and has a resolute expression on her face. Behind her stands a majestic medieval-looking castle, adding a touch of grandeur to the space. For an eye-catching look, I would color the dragon in deep shades of green, with some royal blues and hints of purple to accentuate the creature's majestic power. Add some vibrant pinks to the princess' outfit and surrounding landscape to add a touch of vivid contrast. Finish it all off with some dark grays to bring out the details of the castle and further define the story here.