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