Hi!

I conquered Lumeris sytems with the Craver but the system does not show my player colour to indicate, that it's now mine. They still appear green (playercolour of the Lumeris) even if it's now my ownership.

Am I missing something or is someone experience the same thing?

Hello :)

If you're talking about the sphere of influence, it's normal: captured systems take a certain time to completely fall under your ownership. A feature allowing to track the state of ownership of a system is currently being worked on. 

Don't worry it should change to your color after a certain number of turns!

You can also check the color of the system's label (the rectangle where its name is written: it should colored in your Empire's color.

Cheers!