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