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