The 'color chooser' option has been added to the House and gubernatorial interactive maps; this feature was launched on the Senate map in June. Previously, the only option for creating your map was to click or tap a state or district repeatedly until arriving at the desired rating. This can be a bit cumbersome if you are building a map with all seven available ratings.
The new Color Chooser allows you to select a color/rating such that only one click is necessary on a race to get the desired rating. Check it out in the short video below.