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