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