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