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