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