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