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