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