Purpose – Visual modeling is a powerful tool for knowledge sharing, design thinking and decision making. There are many methods for visual modeling, but the selection of the right ones – is not evident for non-specialist. The authors previously suggested the approach for diagram classification and selection based on a semantic analysis, which links various knowledge types (know-what, know-how, etc.) with corresponding diagram type. The current paper provides and illustrates the resulting method for knowledge diagram classification and selection. The case-study shows the selection and usage of different diagram types within organizational development project in marketing domain of a medium-sized repair service company. Design/methodology/approach – the paper is in line with design science research – a research paradigm in which a researcher answers questions relevant to human problems via the creation of innovative artifacts, thereby contributing new knowledge to the body of scientific evidence (Hevner, Chatterjee, 2010). As Moody (Moody, 2003) and Rescher (Rescher, 1977) emphasized, the validity of a method can only be established by applicative success in practice. The authors demonstrate the use of the method to solve practical problem, so case study was used (Hevner, Chatterjee, 2010). This study involved project document analysis and interviews with project participants. Originality/value –The suggested case study for marketing domain of the medium-sized repair service company demonstrates relevance and applicability of a novel method for knowledge diagram classification and selection. This demonstration also helps to clarify how to use the method and gives directions for future research. Practical implications –The method and its demonstration helps manager to understand the potential of knowledge diagrams, to select and apply diagrams more effectively, to structure complex situations systemically and to shape future prospects clearly.