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