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