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