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