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