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