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)(11,12)(13,17)(14,16)(15,19)(18,20)(21,23)(22,24)(25,26,31,28)(27,30,33,34)(29,36,38,32)(35,37,40,39)(1,3,5,8)(2,6,4,7)(9,11)(10,15)(12,16)(13,18)(14,19)(17,22)(20,23)(21,24)(25,27)(26,30)(28,34)(29,35)(31,33)(32,39)(36,37)(38,40)(1,2,5,4)(3,6,8,7)(10,16)(12,15)(17,23)(20,22)(26,28)(27,33)(32,36)(35,40)(9,12,14,15)(10,11,16,19)(13,20,21,22)(17,18,23,24)(25,28,31,26)(27,34,33,30)(29,36,38,32)(35,37,40,39)(9,11)(10,15)(12,16)(13,18)(14,19)(17,22)(20,23)(21,24)(25,29)(26,32)(27,35)(28,36)(30,39)(31,38)(33,40)(34,37) involution — undirected(1,4,5,2)(3,7,8,6)(9,13,14,21)(10,17,16,23)(11,18,19,24)(12,20,15,22)(25,30,31,34)(26,33,28,27)(29,37,38,39)(32,35,36,40)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.