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