In part 6 of the tutorial series the snakes are given shadows that can easily change color.
The LoonRide site has been publishing a series of tutorials based on recreating the popular game Slither.io in Phaser. This is part 6 in the series: "In this part of the series we will be adding gray shadows below snakes. We will want these shadows to be flexible in that they can change colors, so that we can make a shadow light up when the player is pressing the space bar to speed up. Other than that, we simply need the shadow to stay directly below the snake."