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