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