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