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