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