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