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