Potions are same color.

The potions; Night Vision, Invisibility, Jump boost (not level 2), Fire resistance, speed (not level 2), Slowness, Water breathing, instant health (not level 2), Instant damage (not level 2), Poison (not level 2), Regeneration(not level 2), Strength (not level 2), and weakness all have a purple color. Same for splash potions.