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