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