One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,8,5,6,3,7)(9,10)(11,20,24,36)(12,25,29,34)(13,18)(14,30)(15,19)(16,22,32,23)(17,28,35,27)(21,31)(26,40)(33,37)(38,39)(2,6)(3,4)(9,11)(10,16)(12,26)(13,23)(14,22)(15,24)(17,33)(18,36)(19,32)(20,30)(21,28)(25,39)(27,38)(29,37)(31,34)(35,40) involution — undirected(2,7,6,8)(9,12,13,27,15,29,14,28)(10,17,18,34,19,35,30,25)(11,21,22,37,24,38,23,26)(16,31,20,33,32,39,36,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.