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