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