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