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