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