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