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