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