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