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