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