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