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