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