Abstract : RDF models describe web resources using subject-predicate-object triples. Combined together, these triples form a graph structure, which cannot be easily conveyed by textual syntaxes such as RDF/XML, Notation 3 or N-Triple because of their one-dimensional nature. Visual editors such as IsaViz and RDF Author represent models as editable node-link diagrams, making the graph structure easier to understand compared to textual serializations. However, visual representations are not fully satisfying and have their own problems: diagrams can quickly become big and over-cluttered, and some editing tasks can be more difficult to achieve when dealing with a visual representation of the model. The first version of IsaViz offered partial solutions to these problems, such as a zoomable user interface combined with enhanced navigation capabilities. Those are, ultimately, insufficient, and additional solutions are needed to take advantage of the properties associated with visual representations, in order to offer better and easier-to-understand diagrams. One such solution is GSS (Graph Style Sheets), an RDF vocabulary for describing rule-based style sheets used to modify the visual representation of RDF models represented as node-link diagrams. Possible modifications include changing the visual aspect of nodes and links (color, shape or icon, font, etc.), but also hiding parts of the graph or changing the layout of some elements.