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