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)(11,15)(12,16)(13,14)(17,18)(19,22)(20,21)(23,24)(25,26,31,34)(27,32,35,40)(28,38,36,30)(29,33,39,37)(1,3,4,7)(2,5,6,8)(10,14)(15,18)(16,21)(22,24)(25,27)(26,32)(28,29)(30,37)(31,35)(33,38)(34,40)(36,39)(1,2)(3,5)(4,6)(7,8)(11,17)(12,20)(15,18)(16,21)(27,35)(28,36)(30,38)(32,40) involution — undirected(9,11)(10,15)(12,19)(13,17)(14,18)(16,22)(20,23)(21,24)(25,28)(26,30)(27,29)(31,36)(32,37)(33,40)(34,38)(35,39) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,10)(11,18)(12,16)(13,14)(15,17)(19,24)(20,21)(22,23)(25,29)(26,33)(27,36)(28,35)(30,32)(31,39)(34,37)(38,40) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,12,13,20)(10,16,14,21)(11,19,17,23)(15,22,18,24)(25,30)(26,28)(27,37)(29,32)(31,38)(33,35)(34,36)(39,40)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.