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