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