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