Implementing Graphical User Interfaces (GUIs) for complex control systems (CS) implies many development challenges, especially for prototyping and refining. We propose to improve current practices by introducing a model-based, domain specific approach to GUI development. Our methodology is founded on the assumption that most information to be used for GUI prototyping can be derived by the CS specification itself. We use model transformation techniques for automatic generation of a GUI from a domain specific model. We apply the methodology to the CERN CMS Tracker Cosmic Rack as a case study.