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