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