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