I truly hope we get to see the other 3 colors on actual cars next month, but I believe the renders I have are reasonably close; about 95% on Verdant and Magma. I'm having a difficult time with Nimbus as photos of the samples vary from straight up silver, to a smoothed out warmish silver gray, to a fast transition from bright to dark. I haven't been able to figure out how to replicate that color behavior, so I've did my best to match the inside shot of the warmish gray.
Here are the reference icons for the 3 colors I created for the ones we haven't seen.
Here's a picture of the actual planform samples I used to pull the colors from.
As you can see in the picture above, Nimbus is silver gray with a fast transition to shadow, yet in the image below taken indoors, it looks smoother and warmer.
I've gone with the warm indoor version for the renders I'm posting here.
Just for reference, here's a picture of the actual Hethel Yellow car in China.
And here's my render of Hethel.
With the exception of the lighting difference, you can see by the front of both images the color tone is virtually identical.
Without changing anything else other than the color of the car, here's Magma, Verdant and Nimbus.
If Lotus doesn't post pictures of cars in all the colors next month, I believe these renders are 90-95% close to what they're actually going to look like. Close enough to make a reasonable decision without being surprised by the actual color on a real car.