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