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