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