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