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