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