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