The CIE Supertrain livery came in 1972, same time the Mk2 coaching stock entered service. There was still Black & tan liveried locos in service up to the end of the 1970s; by 1980 everything was Supertrain.
Regarding books, the recently published Rails Through the West would be right up your street, mostly 1970s and nearly all colour.
Also Irish Metro-Vick Diesels is equally good book, covering 1960s-1970s and onwards. Both books are published by Colourpoint, the latter although out of print can still be picked up.
For Videos, Markle Associates have published several DVDs, featuring some archive footage of CIE from 1970s onwards.
They are also the producer of the suger beet DVD you're probably thinking of.
I'm sure there are other sources. One thing though is that there little published in the way of CIE in the late 1960s diesel era, but the above would be very useful anyway.