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