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)(11,14)(12,17)(13,16)(15,20)(18,21)(19,23)(22,24)(25,26,31,29)(27,34,32,28)(30,33,39,37)(35,38,40,36)(2,6)(3,8)(10,11)(15,17)(16,18)(22,23)(26,29)(28,34)(33,37)(36,38) involution — undirected(9,10,14,11)(12,15,20,17)(13,16,21,18)(19,22,24,23)(25,27)(26,28)(29,34)(30,35)(31,32)(33,36)(37,38)(39,40)(2,6)(4,7)(9,11,14,10)(12,17,20,15)(13,18,21,16)(19,23,24,22)(25,28,31,34)(26,32,29,27)(30,38,39,36)(33,35,37,40)(1,3)(2,7)(4,6)(5,8)(9,12)(10,15)(11,17)(13,19)(14,20)(16,22)(18,23)(21,24)(25,29,31,26)(27,34,32,28)(30,37,39,33)(35,38,40,36)(1,4,5,7)(2,3,6,8)(9,13,14,21)(10,16,11,18)(12,19,20,24)(15,22,17,23)(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.