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