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