It could be genetic, it could be an individual thing... perhaps there was an issue during sclerotization (hardening/tanning process during a molt).

Only way to find out! Make babehs!! >=D

I would be tempted to think this is more of a structural anomally due to the softer exoskeleton, the lighter coloration likely resulted from this rather than an a specific pigmentation difference. Regardless, it would be interesting to find out if this is a fluke or something that can be reproduced. I for one would love to see a genetically 'soft' cricket.