If you want the original cable, you can try asking Audio Technica directly.
Service & Repair | Audio-Technica
https://www.facebook.com/AudioTechnicaSEA/
If you don't mind third party cable, would recommend you try the Fiio RC-HD1 cable. IMO it improves the sound as compared to the stock cable too. Even though it's not designed for the M50X, it works with the M50X and should work with the M40X. You can audition it at E1.
FiiO
https://www.facebook.com/E1PersonalAudioSg
You can also try asking around and see if anyone is willing to sell you the straight 1.2m cable (M50X) or coiled cable (M50X or M40X). Try posting in the marketplace here and over at VR Zone.
You can also try asking around and see if anyone your current cable can be repaired.