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