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