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