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