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)(18,24,33,38)(21,34,37,36)(1,2)(3,7)(4,6)(5,8)(9,10)(11,17)(12,24)(13,16)(14,28)(15,19)(18,26)(20,31)(21,35)(22,29)(23,32)(25,33)(27,38)(30,34)(36,40)(37,39) 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)(18,30,33,40)(24,35,38,39)(25,36,26,34)(3,8)(5,7)(9,12,14,26,15,27,13,25)(10,18,16,24,19,33,28,38)(11,21,20,34,23,37,22,36)(17,30,29,35,32,40,31,39)(2,6)(5,7)(9,13,15,14)(10,16,19,28)(11,22,23,20)(12,25,27,26)(17,29,32,31)(18,24,33,38)(21,36,37,34)(30,35,40,39)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.