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)(11,17)(12,26)(13,19)(14,31)(15,20)(16,21)(18,27)(22,38)(23,34)(24,36)(25,37)(28,39)(29,40)(30,33)(32,35) involution — undirected(2,5)(3,7)(9,11)(10,17)(12,13)(14,24)(15,32)(16,25)(18,38)(19,26)(20,35)(21,37)(22,27)(23,29)(28,30)(31,36)(33,39)(34,40) involution — undirected(9,12,15,27,16,28,14,23)(10,18,20,39,21,34,31,26)(11,22,24,13,25,29,32,30)(17,33,36,38,37,19,35,40)(2,5)(6,8) involution — undirected(1,3,4,7)(2,6,5,8)(9,13,15,29,16,30,14,22)(10,19,20,40,21,33,31,38)(11,23,24,12,25,27,32,28)(17,34,36,26,37,18,35,39)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.