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