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