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