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