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