I would color the background in a warm and inviting pastel color. I might even add some stars or other shapes to create a whimsical feeling. The family would be dressed in bright, cheerful colors that compliment each other. I would draw the father wearing a blue shirt and the mother wearing a pink dress. The two children would be wearing bright yellow and green outfits respectively. The garden itself could be colored in shades of green and yellow with a few vibrant flowers. Finally, I would use a bright yellow to bring out the sunlight. By using these colors and textures, I can create a scene full of warmth and love.