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