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