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