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