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