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