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