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