import "github.com/xiegeo/coloredgoroutine"

Just replace

var logger = log.New(os.Stdout, "logger: ", log.Lshortfile)

with

var logger = log.New(coloredgoroutine.Colors(os.Stdout), "logger: ", log.Lshortfile)

So you can easily remove it when you are done debugging and no one will know.

Sample output:

Color template:

Bigger numbered go routines will repeat the colors.