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