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