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