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