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