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