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