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