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