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)(25,26,31,29)(27,32,35,37)(28,33,39,38)(30,34,40,36)(1,3,6,5)(2,7,4,8)(9,11)(10,13)(12,19)(14,17)(15,23)(16,18)(20,24)(21,22)(25,27,31,35)(26,32,29,37)(28,36,39,34)(30,38,40,33)(1,3,6,5)(2,8,4,7)(12,21)(15,20)(19,22)(23,24)(27,35)(28,39)(32,37)(33,38)(9,12,14,21)(10,15,18,20)(11,19,17,22)(13,23,16,24)(25,28)(26,33)(27,36)(29,38)(30,32)(31,39)(34,35)(37,40)(1,4,6,2)(3,7,5,8)(9,11)(10,16)(12,22)(13,18)(14,17)(15,23)(19,21)(20,24)(25,29,31,26)(27,37,35,32)(28,33,39,38)(30,34,40,36)(1,5,6,3)(2,7,4,8)(9,13,14,16)(10,17,18,11)(12,23,21,24)(15,22,20,19)(25,30)(26,34)(27,38)(28,32)(29,36)(31,40)(33,35)(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.