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