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