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