The Nexus Transport Group fleet colours can be found within this document, there are various different liveries to choose from, depending on what DLC's you have in either of the two games.
Official Colour Scheme
We have a wide variety of colour schemes available for both Euro Truck Simulator 2, and American Truck Simulator.
The official colour scheme for Euro Truck Simulator 2 is Canopy & Heavy Duty.
The official colour scheme for American Truck Simulator is yet to be decided.