Hi ! I've juste a little question, so when does a system get your color when you've took it?

Thanks.

I think I've encountered the same issue you are trying to describe here. In my last game I was playing as the Sophons ( blue colour ) and was declared war on by the Lumeris ( yellow colour ) ; I ended up winning the war and captured several of their systems. Despite this, the yellow sphere of influence continued to display on the galaxy map even though the territories now belonged to me. If I looked closely I could see what looked like my blue sphere of influence beneath. I'm assuming this is a bug, and probably doesn't have any material difference on the game, but it would be nice for the galaxy map to update correctly following a successful territorial grab.

Yeah was the same issue, i thought it was a bug too but i wanted to check this here :)