The paper reports on a Knowledge Graph (KG)-based Data Fabric project in the authors’ host institution. The project aimed to lift legacy relational databases that are spread around the institution to an enterprise-grade Ontotext GraphDB server and to provide a visual data navigator to decision-makers. The visualization takes a particular technical approach to be explained in this paper. Complex SPARQL queries are devised not only to retrieve the data to be visualized, but also to gradually transform legacy data towards visual graph structures tailored for diagrammatic navigation through a contextual sliding window. This raises a specific requirement for graph transformations that are valuable as reusable patterns that are more comprehensible compared to the common visual tools we encountered for KG navigation. Therefore the work belongs to the artifact-building genre advocated by Design Science and suggests the importance of a dedicated research direction that should account for the distinction between the semantics of what is stored in the KG and the semantics of visual constructs, of how things are graphically presented – with the help of metadata labelled here as “visualization semantics”, a viewpoint that is well established in the field of diagramming but ignored for a long time by the visual interfaces emerging from the KG community.