One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(6,7)(9,10,15,30,14,19,13,18)(11,20,28,16,23,35,22,32)(12,24,29,34,27,17,26,36)(21,37,39,40,38,33,25,31)(1,2,4,5)(3,7,8,6)(9,11)(10,16)(12,25)(13,28)(14,23)(15,22)(17,33)(18,35)(19,32)(20,30)(21,26)(24,37)(27,39)(29,38)(31,34)(36,40)(9,11)(10,16)(12,21)(13,28)(14,23)(15,22)(17,31)(18,35)(19,32)(20,30)(24,40)(25,29)(26,39)(27,38)(33,36)(34,37) involution — undirected(1,3,4,8)(2,6,5,7)(9,12,14,27)(10,17,19,24)(11,21,23,38)(13,29,15,26)(16,31,32,40)(18,36,30,34)(20,37,35,33)(22,39,28,25)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.