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