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