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