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