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