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