System- Theoretic Process Analysis (STPA) is a relatively new hazard analysis technique. Several tools supporting the STPA process already exist. However, they are mostly textual. In this paper we present a Domain Specific Language (DSL) for STPA with an automatic visualization of the STPA components. This combines the advantages of textual and graphical approaches. The DSL is implemented with open source tooling, realized as a Visual Studio Code Extension using Langium for the language server and Sprotty for the visualization. A comparison suggests that the DSL has potential to be a good alternative to other STPA supporting tools.