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