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