Artists such as Riley and Seurat based much of their art around knowledge of specific 'qualities' of colour. If you've ever bought a house/decorating magazine, you may have seen a thing called a colour wheel, which shows how colours harmonise or clash. Placing certain colours, shades and tones together can create quite different effects on the eye. For example, Seurat believed that colours could 'vibrate', depending on which colours were placed together. Riley is on doubt influenced by the same beliefs - her paintings aren't merely stripes in any old shade - I would imagine the colours will have been very specifically chosen for the effect they produce.
I'm no expert (I am recalling this from a dissertation on Seurat I did over 12 years ago) but hope it gives you something to start from.