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