 Cayley held several art exhibitions and in 1932 one of his paintings was presented to King George V.

Meanwhile, the prolific Cayley was working on a much more ambitious project – his "big bird book".From about 1918 until the time of his death in 1950, Cayley was painting subspecies, plumage stages and eggs (now lost) for the entire range of known Australian birds.Sadly, the project was incomplete at the time of his death, despite the illustrations being all but finished.