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