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