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