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