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