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