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)(11,19)(12,23)(13,27)(14,17)(15,22)(16,26)(18,29)(20,36)(21,35)(24,34)(25,32)(28,33)(30,37)(31,38)(39,40) involution — undirected(9,11,13,22,14,21,29,38)(10,15,18,19,17,31,27,35)(12,24,25,39,26,20,28,37)(16,30,32,36,23,40,33,34)(2,5)(6,8)(9,12,14,26)(10,16,17,23)(11,20,21,24)(13,28,29,25)(15,30,31,40)(18,33,27,32)(19,34,35,36)(22,39,38,37)(11,21)(13,29)(18,27)(19,35)(20,24)(25,28)(32,33)(34,36) involution — undirected(1,3,4,7)(2,6,5,8)(10,17)(15,31)(16,23)(18,27)(19,35)(30,40)(32,33)(34,36)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.