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