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