Children of Ruin is the sequel of Children of Time, I strongly suggest you read the first book or you'll have quite an hard time to understand certain things.
I'm reading Children of Ruin right now and it's quite funny finding this article here right now. :)
I recall an Arthur C Clarke story (can't remember if it was a short or a novel) that touched on the same idea. In the story, the squid's imaging abilities were very advanced, almost TV like.
>> 'Arthur C. Clarke used giant squid in many of his works. In The Deep Range, a squid of exaggerated size is captured and exhibited. In the short story "Big Game Hunt", a device capable of controlling the behavior of invertebrates is used in an attempt to capture and film a giant squid. In Childhood's End, one of the characters stows away on an alien spacecraft by hiding inside a model of a giant squid battling a whale.'
There's quite a bit of light/color-based communication from/between "octospiders" in his Rendezvous with Rama series. Also depicted in (mediocre) computer game form!
A bit off-topic since I don't recall it discussing communication a lot, but Stephen Baxter's Time touches on genetically engineered squids for manning space exploration missions. As always, the short lifespan of these creatures is both a blessing and a curse...
https://www.goodreads.com/book/show/40376072-children-of-rui...