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