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