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