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