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