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