Thanks for any ideas folks may have about this. I read the book as a schoolkid in the late 70s or early 80s. I thought it would be a simple search; I'm pretty sure it was called something obvious like "Space Cats," but I've searched many variants of that and haven't been able to find it. It was about a boy and a girl, I think brother and sister, who are brought to a planet of cats, where all communication, with other beings and with the machines that dispense their food, is by telepathy; there is no speech. The kids are first put through this machine which cleans them and dresses them in cozy suits. It was for fairly young kids, I think--I was probably 10 when I read it. The cover of the paperback copy I had definitely included the boy and girl in their yellow fuzzy suits that had been dispensed by the cleaning machine.
I suspect you're thinking of Star Ka'at and/or the sequels, by Andre Norton:
Two Earth children are taken to the world of the Star Ka'ats, intelligent, telepathic cat creatures.
The timing is right (1976) and they were for young readers; I can't find a sufficiently detailed synopsis to confirm whether or not the specific details you mention match up, but they did at least involve a brother and sister and telepathic cats. (Plus, of course, the title is very close to what you thought it was, while still sufficiently different to make a Google search fruitless.)
Possibly this was the cover on the copy you had? It has the yellow suits.