Change the colour without disturbing the drawing.
Colour and geometry are separate axes here. Recolour swaps the palette and leaves every shape precisely where it was, so you can run twenty colourways past a composition without losing the composition.
Each system suggests palettes that tend to suit it. You can also lock individual colours, and a reroll will leave those alone.
The background can come from the palette, be a flat colour of your choosing, or be transparent. Transparent means transparent. No system quietly draws a white rectangle behind its work, so the exported SVG drops cleanly onto whatever is underneath.