Green is hard to get in some species. All eight of my Chinese mantids were brown! Except one that was somewhere in between for two instars. Your mantis is beautiful in both colors, I love the forearms on Lineolas!
Yeah my lineola females were all brown or brownish as nymphs. Dunno if any of the ones I sold that were green stayed green. All males that I got left turned green, 2 more to go, 1 is molting right now a d 1 is brown sub adult. There is one green sub adult female I am waiting to see how she does but I like the brown ones as well, there are actually pretty cool. Like, Rhombodera females I can't tell one from the other, but Sphodromantis viridis I have 3 gals one light brown, one darker brown and one minty green. I loved the colour variations on lineola nymphs, green, yellow, brown, dark brown, almost white, khaki...
She looks like she is enjoying her fly, nice photo. I have a few myself like that, and it's always amazing how fat the flies look when being ate. I'm like you on the coloring. Each different one has it's perks, but green is the one that seems to be the "true" mantid color.