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