Understand now has a selection of predefined themes that let you quickly change the look and feel of the editor. These themes can be accessed under Tools->Options->Editor->Styles. The Predefined: section at the top of the page lets you select the theme you want, and you can customize the theme to your liking.
Here are what several of the themes look like:
If you like most of a predefined theme but want to “tweak” a few items, make sure to take a look at the options available for each supported language.
For Application Styles, go to Tools->Options->User Interface->Application Styles and select your custom options there. Note that the ‘Use Editor Colors’ button is very useful for quickly matching the Editor Styles to the Application Styles.
Happy Coding and Color Customizing!