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