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