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