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