Denser than lead shot like the old Remington HD or the TSS shot in pellet sizes of #2,3,4,5 in 1-ounce weight in a properly choked 20 gauge should kill coyotes well enough to about 30 yards. The denser than lead stuff is hard and breaks bones well, it penetrates hide and muscle well also. With smaller pellets like #4, the pellet count is much higher and fills the pattern better. If you can manage a center-dense core, better yet. Shoot them in the head and be ready to apply more shot to the problem if they don't immediately go down for the count. Look for a good tungsten (NOT steel shot) turkey or waterfowl load.
