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