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