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