Hi Kirley,
The 'Supertrain' livery is the plain orange and black livery introduced by CIÉ as a successor to the 'Black & Tan' colour scheme. I forget the exact year, but the change-over began in the early-mid '70s, and began to be phased out when Irish Rail was formed in 1987, although it survived well into the '90s on a few locos, with the CIÉ roundel replaced by the IR 'points' logo.
An example of an 071 in the livery:
An A class:
And some Mk2s:
I'm not sure of the exact shade of orange, but it was a tad deeper than the shade used for the IR/IÉ colour schemes.
The A, C, 121, 141/181 and 071 classes all received the livery (or the ones that remained in service at that point in some cases). A small number of the B101 Sulzers were also repainted in Supertrain colours, while others remained in the Black & Tan or black & white trim liveries.
The only coaches to receive the livery were the Mk2s and Mk3s, and their generator vans. All other coaching stocked remained as it was, although the Cravens received a minor livery alteration post-1980s.
JHBAchill, Mayner or some of the others may be able to provide more information.