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