You can change the colors used by circuit and system elements from the Options > Environment Options menu and the Colors tab.
These settings are applied globally for your work with the AWR Design Environment
Starting in Version 14.01, you can now change this color per element. To do this, double-click on the element and click on the Symbol tab.
The dialog looks like:
Click the Use custom color checkbox and then click on the Symbol Color button to choose which color to use.
You can set this color in library xml files if you develop your own library of parts.