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