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