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