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