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