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