public Color getVertexColor(Address address) {
		ObjectPropertyMap<SaveableColor> propertyMap =
			programUserData.getObjectProperty(FunctionGraphPlugin.class.getSimpleName(),
				COLOR_PROPERTY_NAME, SaveableColor.class, false);
		if (propertyMap == null) {
			return null;
		}

		SaveableColor saveable = propertyMap.get(address);
		if (saveable == null) {
			return null;
		}

		return saveable.getColor();
	}
Note: this method does not clear group vertex locations.
@param functionGraph function graph
Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/mvc/FunctionGraphVertexAttributes.java