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