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