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