This fantastical valley is full of opportunity for exploration and creativity! The bright blue sky creates a peaceful atmosphere, while the jagged mountains anchor the valley and provide a sense of adventure. The river is majestic and inviting, and a bright yellow could be used to create a dramatic contrast to the purple hues of the mountains and the greens of the valley floor. You could even color the rocks a deep brown or black to create an even richer contrast. The sky could be painted in a light blue, with whispy white clouds, or a deeper blue with orange-y sunset tones. The possibilities are endless, and it is up to the artist to make their own decisions!