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