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