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