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