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