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