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