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