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