Looking at the rear panel of the radio we find all the connections we need for audio/ptt/CAT:
From the manual we get the pinouts:
Same connections can be found in Kenwood TS-480 kit:
The RX/TX pinout of the DB9 cable appears to match that of the Kenwood, but it is possible that the signal names are given from the perspective of the computer and are reversed. I have cables in both variants so if one doesn’t work let me know and we’ll do the exchange. Alternatively, this thing exists: