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