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