The Kermeta Graphical Editor is a view of the Kermeta model as a class diagram. It is generated with the tool "Topcased". The file containing the presentation informations is a *.kmdi. The *.kmdi is associated with a *.km file. The *.kmdi and *.km files must be in the same folder.
We can open it, simply select and right-click "Open with / Kermeta class diagram"
In order to create a Kermeta class diagram you have 2 ways.
Create a class diagram and the Kermeta model from scratch. Select the project or the folder where you want create the class diagram and right-click "New / Other / Kermeta / New Kermeta class diagram". Change the model name if you want.
Create a class diagram from an existing Kermeta model. Select the existing km file and right-click "New / Other / Kermeta / New Kermeta class diagram".