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