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