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