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