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