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