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