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