Take a look at this project we designed in Las Colinas, TX:

https://www.houzz.com/photos/las-colinas-modern-modern-pool-dallas-phvw-vp~27999795

We utilized colored, salt-finished concrete pavers on a decomposed granite bed. I won't say that the pavers are inherently "cool" in nature, but they are certainly a bit cooler than traditional concrete decking or aggregate. And seeing as how you can choose from multiple colors, you could either find a single color of paver that would work with your varying brick coping, or you could select a few different colors that would change in the same ways that your brick does.

We didn't know about this product/company at the time this particular project was being designed, but here's a great company that specializes in these types of products:

http://www.hartstonetile.com/

They came up with their own special concrete formula and they use it to make concrete pavers and tiles. And these Hartstone pavers actually DO stay much cooler than traditional concrete.

And just as another idea, take a look at this photo from Hartstone's portfolio. You could implement a colored border/band around your brick coping similar to what's pictured here, and then incorporate a number of different colors or patterns outside that.

http://www.hartstonetile.com/tiles-and-pavers/#foobox-1/21/Hartstone-11.png

Just a few unique ideas. I hope this was helpful!