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