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