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