color-indent
Use colors to show in a non intrusive manner different indentation levels.

Installation
You can install via apm:
apm install color-indent
Or, just search for color-indent inside Atom's package panel.
Features
I once saw something like this some years ago. Unfortunately I don't remember where, but since I always wanted it, I'm building it now.
- Choose your own color.
- Use a custom width.
- Choose identation depth.
Usage
Just type and see how the tabulation color is filled.

Choose a custom color

You can also toggle the colors if you need to deactivate it or reactivate it quickly.
Go to the Atom Command Palette and choose color-indent: toggle.