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