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