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