Thats what I originally thought, but changed it to green.
Well, as far as I know, [CuCl4]2- is yellow. I didn't know that more Cl ligands would be added to the Cu.
If I remember correctly, the solution turns green if you have insufficient Cl since the pale blue (original) solution and the yellow CuCl4 mix to make the solution green. They asked for the colour of the actual complex so I just put yellow.