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