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