I would color the picture in soft pastel shades, creating a warm and inviting effect. I would color the background with a soft shade of yellow, like lemon, to match the cheerful mood of the girl. The girl herself would be colored in a light pink hue, and I would use lighter colors for her dress and shoes. I would keep the purse black and white with a few hints of yellow throughout to create a contrast. The small hearts around her would be a slightly brighter pink, adding a vibrant energy to the scene. Finally, I would give her hair a gentle ombre color, ranging from a light brown to a deep blonde. With these colors, the image would be vibrant and inviting.