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