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