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