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