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)(25,26,31,33)(27,34,28,32)(29,38,39,35)(30,36,40,37)(1,3,5,8)(2,6,4,7)(25,27,31,28)(26,32,33,34)(29,36,39,37)(30,35,40,38)(10,15)(11,16)(17,22)(18,23)(26,33)(27,28)(35,38)(36,37) involution — undirected(1,2,5,4)(3,6,8,7)(9,11,14,16)(10,12,15,20)(13,18,21,23)(17,19,22,24)(25,28,31,27)(26,34,33,32)(29,37,39,36)(30,38,40,35)(1,2,5,4)(3,6,8,7)(9,12)(10,16)(11,15)(13,19)(14,20)(17,23)(18,22)(21,24)(25,29,31,39)(26,35,33,38)(27,36,28,37)(30,32,40,34)(1,4,5,2)(3,7,8,6)(9,13,14,21)(10,17,15,22)(11,18,16,23)(12,19,20,24)(25,30)(26,36)(27,35)(28,38)(29,34)(31,40)(32,39)(33,37)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.