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