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