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