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