The carapace of the falcon was painted in the following way.

The light green is "putrid green" (all the colour names are from Citadel's piant range) and the darker green is "emerald green" the different shades of green are achieved by applying a few layers of "orc flesh" wash. 

I start off with the putrid green as a base colour and then paint the circular patterns on with the emerald green. I then coat the lot with orc flesh wash (dark green ink).   The orc flesh wash darkens everything so I paint with the same two coloured paints again, making the pattern a bit smaller, so the total effect looks like 4 or 5 shades of green.

Details like the jewels were added last.

I thought up this colour scheme while I was thinking about how the Eldar make their vehicles out of wraithbone and that the vehicles are bio-mechanical contructs. 

I had the idea that the outside of the tanks etc. would respond to their driver and enviroment in a similar way that an octopus does. 

If I was making a movie with Eldar in it, I would have their vehicles changing the size of the spots and patterns in an emotional way. 

For eg. when the vehicle was fighting the light greens would contract and it would go a series of dark green that would look like it was boiling.