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