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