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