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