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