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