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