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