You will have to edit the widget because as far as I can remember the widget does not support custom markers.
The Google Maps widget has a property 'Enum based marker images' in the 'Appearance' part where you can configure different images. The entity what contains the address and GPS info should have an enum attribute defining what tye of location marker image should be used.. The hardest part is finding the right images, but google can help you a lot.
Download the latest Google maps module. In the configuration Appearance you have the option Enum based marker images. Here you can select an enum with your custom marker images.