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