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