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