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