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