Divi uses the WordPress Theme Customizer interface to allow you to adjust your theme's colors quickly and easily. To use the Theme Customizer, click the Appearances > Customize link. This will launch the customizer along with various color options.
Once you have launched the customizer, you will see various color options and font options. Adjusting the colors will change the live preview on the right. Once you have chosen your desired colorscheme, simply click save to push the changes to your live website.