Introductory slide to this presentation points out that there is no standard way to represent patterns as a diagrams. Some pattern writers use UML diagrams to represent object-oriented concepts, some take screenshots, others draw a non-formal diagram. There is no consensus in the way patterns are presented. Not all patterns even have a diagram representation. In such situation, graphical pattern representation is under used. The diagrams do help clarify concepts, but because of diversity of methods that can represent patterns graphically, this representation cannot be used for pattern identification and pattern retrieval. 

Below are several examples taken from the literature in the following order: Model View Controller [2], Shaper representation [6], Adapter pattern [2], HOPP pattern [5].