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