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