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