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