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