Warning: Don't do this, if you aren't confident with tinkering around.
I'll describe the procedure for Mac, somebody else could describe it for Windows or Linux ;).
Adding a new background colour
I've made a screenshot of the green in the Dashboard and resized it to 100px x 100px (see attached ZIP). You can use this colour as a background or only as a border colour (between CafeTran's panes), by adjusting the slider above the Grid.
The menu path:
The disk folder path:
Unzip the attached file, place it in the "colors" folder (see above). Select the background colour and adjust its transparency.
You can add any colour you like, this way.
Adding your own icons
Igor will provide coloured icons but if you cannot wait until then or if you want to add your own icons, you can find CafeTran's icons (grey and coloured) here.
Navigate to the graphics path (see above) and down to the icons subfolders. Place your icons there.
Personally, I'll probably end up with keeping the grey icons, and inserting some coloured icons for tasks that I use most frequently (Add terms to glossary etc.). A Mix and Match layout.
A nice preview file with all coloured icons and their file names. If someone wants to invest the time to collect all coloured equivalents of the current selection in CafeTran's icons folder, please don't hesitate to upload them as a ZIP here ;). So that others don't have to do that themselves.
And a screencast.
These coloured icons are nice too!
I think that I'll change the Add note icon to grey, since it looks too much like the old Add term to glossary icon for me (I have to get used to the new pencil icon).