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