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