As this example shows, it will place rank or file markers close to the board when a slanted row is treated as a rank or file.
However, your ASCII diagram does not seem to have them arranged in any manner supported by the Diagram Designer. It looks like you are using numbers to designate vertical diagonals as files on a board with horizontal ranks in the manner that Pritchard used for hexagonal games. That is not supported. When dealing with hexagonal boards, it uses only orthogonal rows for ranks and files. However, it might be possible to use perpendicular axes with a custom image of a hexagonal board, though I have not tried to do so myself.
As this example shows, it will place rank or file markers close to the board when a slanted row is treated as a rank or file.
However, your ASCII diagram does not seem to have them arranged in any manner supported by the Diagram Designer. It looks like you are using numbers to designate vertical diagonals as files on a board with horizontal ranks in the manner that Pritchard used for hexagonal games. That is not supported. When dealing with hexagonal boards, it uses only orthogonal rows for ranks and files. However, it might be possible to use perpendicular axes with a custom image of a hexagonal board, though I have not tried to do so myself.