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