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