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