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