A lot of the color slides of her were taken during her scrap in 1950 - perhaps the majority.
I believe there is an old thread here at ET listing the color images - there is something like 12 or 14? I think the color photo that started this thread is or was there as well, but a different copy. And yes, she was repainted for Canadian service in 1948.
Here are the threads - the last one has 2 lovely images in it.
I don't know if anyone else has posted this or not, but I found a color clip of the striking of Aquitania's house flags as she is departing for the breakers on You Tube. Just search for Aquitania. Great video of the old girl.