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