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