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