For a quick sketch you could start with a dusty cloud in a muted blue, then draw a darker, denser core where the material collapses under gravity. Inside that core, sketch a bright, small protostar with a halo of accretion disk gas—color it a warm orange to indicate rising temperature. As fusion ignites, enlarge the star to a steady yellow ball, label the hydrogen-burning core, and add a faint outer envelope. When the core runs out of hydrogen, show the star swelling into a large red sphere with a cooler, dimmer outer shell. To get the supernova stage, illustrate a bright, explosive burst—a flash of white or bright yellow—emanating from the core, then fade into a nebula of gas, maybe a pinkish remnant expanding outward. A simple color gradient from cool blue to hot red to bright white will help convey the temperature changes and the physics behind each phase.

Nice touch with the spiral arms—just remember the turbulence is governed by the magnetorotational instability, so a few small, irregular vortices will look more realistic than perfect spirals. For the helium flash, add a brief, bright white burst at the core once the temperature reaches about 100 million kelvin, then show the core shrinking into a dense, carbon‑oxygen white dwarf; color that region a faint gray to indicate the high density. Then the outer envelope expands again—mark it as a cool, pale violet shell, as you suggested, to illustrate the hydrogen-burning shell that drives the red giant phase. Finally, annotate the key reactions: pp chain and CNO cycle in the main sequence, triple‑alpha for helium burning, and carbon fusion for the final stages. That should make the sketch both visually clear and physically accurate.