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