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