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