I have the 05' TL version and I didn't see a place where you could choose the color for the navigation screen.

 

Hmmmm. I have an 08 and in the setup menu it allows you to change back ground color and also day/night colors. Not sure if our Navi's are that different as far as setup menu.

 

ya you can change background color in 07 as well

 

you can change the background color on the menuboxes on my 06, so I would think its possible in an 05 as well, however the change is not the whole screen.
It's kind of hard to explain , but go to set up screen #3, background color, and choose blue,grey,amber, or red.

 

It's not a very noticeable thing on the '04 and the '05. It's such a minor thing that I think it's not worth bothering. It does not affect the main map display nor the main menu with the buttons. If you select a POI, you'll see the color change in the background of the box that displays the address and phone number (and, again, it's a very subtle change).