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