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