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