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