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