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