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