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