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