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