Although yEd has no feature that does exactly that, it is possible to use custom properties and the properties mapper to get close to the desired result.
Step 1 would be to create properties for both nodes and edges that store some kind of version information. E.g. an Integer property where 1 means January, 2 means February, and so on. Custom properties are created using "Edit" -> "Manage Custom Properties".
Step 2 would be to create node and edge property mappings that use those version properties to highlight new nodes and edges e.g. by coloring all old edges gray and new edges blue. If the version properties are indeed of type Integer, range mappings make it possible to create rules like "version 1 to 3 to gray" and "version 4 to blue". Property mappings are created and applied using "Edit" -> "Property Mapper".
This approach can be tested with this sample graph that has a Revision property for nodes and edges and these property mapper settings to color old nodes and edges. To test the property mapper settings, please replace the propertiesmapper.xml file in your yEd profile directory with the attached one. (Backing up the existing propertiesmapper.xml first is a good idea to be able to restore existing mappings later on.)