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