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)(25,26,31,36)(27,37,38,33)(28,34,40,30)(29,39,32,35)(9,11,13,19)(10,14,15,17)(12,20,21,18)(16,24,23,22)(25,27,31,38)(26,33,36,37)(28,32,40,29)(30,35,34,39)(2,6)(7,8)(25,28,32,38,31,40,29,27)(26,34,35,33,36,30,39,37)(1,3,5,4)(2,7,6,8)(10,15)(14,17)(16,23)(22,24)(25,29,31,32)(26,35,36,39)(27,28,38,40)(30,33,34,37)(1,4,5,3)(2,8,6,7)(9,12,13,21)(10,16,15,23)(11,18,19,20)(14,22,17,24)(25,30,29,33,31,34,32,37)(26,28,39,27,36,40,35,38)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.