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