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)(11,13)(12,20)(14,16)(15,19)(17,23)(18,24)(21,22)(26,31)(28,34)(32,38)(36,40)(2,5)(6,7)(9,11)(10,15)(12,21)(13,16)(14,19)(17,22)(18,23)(20,24)(27,35)(32,38)(36,40)(37,39) involution — undirected(1,2)(3,6)(4,5)(7,8)(10,16)(13,15)(17,20)(22,24)(25,26)(27,32)(28,33)(29,34)(30,31)(35,38)(36,39)(37,40) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,12,14,23)(10,17,16,20)(11,18,19,21)(13,22,15,24)(25,27)(26,32)(28,36)(29,37)(30,35)(31,38)(33,39)(34,40)(1,3)(2,6)(4,8)(5,7)(9,11)(10,15)(12,21)(13,16)(14,19)(17,22)(18,23)(20,24)(25,28,30,34)(26,33,31,29)(27,36,35,40)(32,39,38,37)(9,13,14,15)(10,11,16,19)(12,22,23,24)(17,18,20,21)(25,29,30,33)(26,34,31,28)(27,37,35,39)(32,40,38,36)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.