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