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