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