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