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