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