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