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