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