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)(28,34)(29,35)(30,38)(31,33)(36,39)(37,40) 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)(26,32)(28,37)(29,30)(31,36)(33,39)(34,40)(35,38)(1,3,6,7)(2,4,8,5)(10,14)(15,21)(16,22)(23,24)(26,33)(27,36)(30,34)(35,37)(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)(26,34)(27,37)(29,39)(30,33)(31,38)(32,40)(35,36)(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)(26,35)(27,34)(28,32)(30,36)(31,40)(33,37)(38,39)(1,5,6,4)(2,7,8,3)(9,10)(11,15)(12,16)(13,14)(17,23)(18,21)(19,24)(20,22)(25,30,31,34)(26,28,33,38)(27,29,36,40)(32,37,39,35)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.