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