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