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