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