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