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