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