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