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