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