Diagrams are an effective and popular tool for visual knowledge structuring. Managers also often use them to acquire and transfer business knowledge. There are many currently available diagrams or visual modeling languages for managerial needs, unfortunately the choice between them is frequently error-prone and inconsistent. This situation raises the next questions. What diagrams/ visual modeling languages are the most suitable for the specific type of business content? What domain-specific diagrams are the most suitable for the visualization of the particular elements of organizational ontology? In order to provide the answers, the paper suggests light-weight specification of diagrams and knowledge content types, which is based on the competency questions and ontology design patterns. The proposed approach provides the classification of qualitative business diagrams.