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