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