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