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