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)(25,26)(27,34)(28,38)(29,33)(30,31)(32,37)(35,36)(39,40) involution — undirected(1,2)(3,7)(4,5)(6,8)(11,17)(14,21)(18,23)(22,24)(26,30)(29,38)(32,34)(36,40) involution — undirected(2,5)(6,7)(9,10,13,16)(11,14,17,21)(12,15,20,19)(18,22,23,24)(25,27)(26,32)(28,39)(29,40)(30,34)(31,37)(33,35)(36,38)(9,10)(11,14)(12,15)(13,16)(17,21)(18,22)(19,20)(23,24)(25,28)(26,29)(27,35)(30,38)(31,33)(32,36)(34,40)(37,39) 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)(25,29,31,38)(26,33,30,28)(27,36,37,40)(32,39,34,35)(1,3)(2,6)(4,8)(5,7)(9,12)(10,15)(11,18)(13,20)(14,22)(16,19)(17,23)(21,24)(25,30,31,26)(27,34,37,32)(28,38,33,29)(35,40,39,36)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.