In Jain cosmology, Sanathkumar (Sanatkumara) and Mahendra are names of heavenly beings (devas) who live in the upper realms of the universe. The concept of lesya (the color/tinge of the soul due to mental state) is about the soul’s karmic condition, not a fixed label for particular devas. There is no canonical rule that assigns a specific lesya to these two heaven-dwelling gods. The lesya colors (black, blue, grey, red/tejo, yellow/padma, white/sukla) describe the ethical and mental state of a soul, usually discussed in the context of living beings and the path of karma; how these colors relate to the devas themselves is not fixed in Jain scripture. Different Jain traditions (Digambara vs. Śvetāmbara) emphasize the same general framework of lesya, but there is no distinct, tradition-wide assignment of a particular lesya to Sanathkumar or Mahendra.

If you want a deeper, text-based discussion on lesyas and how they are described in Jain writings, I can share the core meanings and the traditional categories.