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