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