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