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