Just turning it all the way off works.
Since the GF is more of computer appliance than a networking device, it cannot sleep (like a laptop or desktop computer) because it has to stay in constant communication with off site servers to respond to requests from more than one device and maintain consistent temp, positioning and optical recognitions.
For those with highly computerized refrigerators (that are cloud connected), their frig does not go into a computer sleep mode due to lack of use. It is an appliance.
And unlike a network copier/printer, there are safety and integrity checks that a laser unit needs to verify and maintain. I guess the GF could go into a computer sleep mode, but do you want to wait the 60 to 120 seconds with nearly every print job (wake up, alignment and calibration process) because it had to go into a computerized sleep?
Walking up to the GF and turning it on, wait the initial 60 to 120 seconds once before using it for one or more jobs and then turning it off unit the next time (hours, days or strangely weeks later for the next job) makes more sense that a built in sleep mode.