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