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