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