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