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