1. Call the “Theme Colors” dialog box any way you like (see How to change the color scheme of the presentation to a different preinstalled color scheme). At the bottom of the dialog box select “Customize Colors…”
2. In the opened window “Create New Theme Colors” where you can specify the colors you need.
3. At the bottom of the window specify the name (“Name” field) of a new color scheme.
4. Click “Save”. Color scheme has been created.