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