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