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