Homey works best if it is never powered off. This way, it can stay in touch with your devices and the interfaces in a solid way. When Homey's LED ring is too visible to your liking, you may rather change the idle mode instead of turning Homey off.
When, after all, Homey really needs to power off (for instance you want to move it to a different location), you can just unplug Homey from the wall socket, and plug it back in to turn it on again.
NOTE: Do not unplug when Homey is updating itself (showing a purple loading animation)! Doing so may corrupt the update.