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