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)(25,26,31,35)(27,34,30,32)(28,38,33,29)(36,40,39,37)(1,2,5,6)(3,7,4,8)(9,11,15,13)(10,16,19,20)(12,21,18,23)(14,22,17,24)(25,27,31,30)(26,32,35,34)(28,39,33,36)(29,37,38,40)(1,3,5,4)(2,7,6,8)(9,11,15,13)(10,16,19,20)(12,21,18,23)(14,22,17,24)(25,28,31,33)(26,29,35,38)(27,36,30,39)(32,40,34,37)(9,12,15,18)(10,17,19,14)(11,21,13,23)(16,24,20,22)(25,29)(26,33)(27,37)(28,35)(30,40)(31,38)(32,36)(34,39)(9,13,15,11)(10,16,19,20)(12,23,18,21)(14,22,17,24)(25,27,31,30)(26,34,35,32)(28,36,33,39)(29,37,38,40)(1,4,5,3)(2,8,6,7)(9,14,15,17)(10,18,19,12)(11,22,13,24)(16,23,20,21)(25,30,31,27)(26,32,35,34)(28,39,33,36)(29,40,38,37)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.