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