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