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