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