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