It's not exactly straightforward as there's no API for this (afaik) so you'd have to mess with chunk manipulation.
Plus the chunks for sends are stored on the
receiving tracks.
So you'd have to find the correct <AUXMUTEENV subchunk for send x on the receiving track and manipulate the VIS line.
https://wiki.cockos.com/wiki/index.p...tions#Envelope
(Someone correct me if there's a more straightforward way.)
edit:
You probably know anyway, there are SWS/BR actions to show mute send envelopes, but not send X specific.