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