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