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)(11,14)(12,15)(13,16)(17,24)(18,22)(19,21)(20,23)(25,26,31,38,30,28,29,33)(27,32,39,40,35,37,36,34)(2,5)(6,7)(9,11,13,19,12,18,20,17)(10,14,16,21,15,22,23,24)(25,27,29,36,30,35,31,39)(26,32,33,34,28,37,38,40)(10,15)(11,17)(13,20)(14,21)(18,19)(22,24)(25,28,30,26)(27,34,35,40)(29,33,31,38)(32,39,37,36)(1,3,4,8)(2,6,5,7)(27,35)(32,37)(34,40)(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.