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