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