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