Groovy templates can be overriden thanks to extension mechanism. Here are steps to override a template of Organization portlet.
Take a look at
This file contains the template definitions of the Organization portlet.
UIOrganizationPortlet.gtmpl file and put it in
Copy the existing content from
UIOrganizationPortlet.gtmpl of Step 1
then modify your file, for example change the color of text and background on the toolbar.
Refresh the browser if you are running eXo Platform at the developer mode. You will see your modification take effect on the Organization portlet.
If you are not running eXo Platform in the developer mode, you will have to restart the server.