Yes, you can paint your aluminum sheet roof after installation. However, it's crucial to ensure the surface is clean and free of any contaminants. Use a primer specifically designed for aluminum to enhance adhesion and durability. Apply a high-quality paint suitable for metal surfaces, following the manufacturer's instructions carefully. This process can help protect the roof from weathering and enhance its appearance, but it's recommended to consult with a professional to ensure the best results and longevity of the paint job.