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