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